The present disclosure relates to a method for battery management of a battery which has multiple battery cells and which is equipped with a charge state balancing system and with a battery management system for monitoring the battery functionality. The present disclosure also relates to a computer program, a battery management system, a battery system, and a motor vehicle which are configured for carrying out the method.
Electronic control devices are increasingly being used today in the automotive field. Examples of this include engine control units and control devices for ABS or the airbag. One current research focus for electrically driven vehicles is the development of high-performance battery packs with associated battery management systems, i.e., control devices which are equipped with software for monitoring the battery functionality. Among other things, battery management systems ensure the safe and reliable function of the deployed battery cells and battery packs. They monitor and control currents, voltages, temperatures, insulation resistances, and other variables for individual cells and/or the entire battery pack. With the aid of these variables, management functions may be implemented which increase the service life, reliability, and safety of the battery system.
Battery management systems are made up of a plurality of control devices on which individual software functions run. Depending on the number of battery cells, the number of sensors, and the distribution of the battery modules across different installation spaces in the motor vehicle, a control device topology results including a main control device and multiple subordinate sensor control devices for detecting the measured value directly at the individual battery cells and battery modules. The detected data are exchanged between the control devices via a communication channel.
For balancing voltages, for example, due to unequal wear or aging of the battery cells, it is known to carry out charge state balancing (cell balancing), in which the battery cells having a high charge state are aligned with the battery cells having a low charge state. For this purpose, currents are conducted across charge state balancing resistors (so-called balancing resistors) as required, and the battery cells are discharged in a controlled manner. The primary control device determines the charge state balancing requirement. This device passes the request for carrying out the charge state balancing to the sensor control devices.
DE 10 2008 002 100 A1 demonstrates a method for charge state balancing of vehicle batteries, wherein the charge state value of the battery cells is preferably ascertained during a quiescent phase via a voltage measurement. For example, suitable points in time are considered to be immediately following an “ignition on” action or following an activation of a control device which carries out the measurement. From the charge states of the individual battery cells, an amount of charge is calculated by which each cell must be discharged until the charge state corresponds to that of the weakest battery cell.